A PSSR inspection is the periodic examination of a workplace pressure system carried out by an independent competent person under the UK’s Pressure Systems Safety Regulations 2000. It follows a Written Scheme of Examination that identifies which parts of the system need checking and how often. If your equipment falls within the regulations and you cannot produce a current examination report, you are operating illegally, and the Health and Safety Executive can shut you down on the spot.
Which Equipment Needs a PSSR Inspection
The regulations apply to pressure systems used at work that contain a “relevant fluid.” That means one of three things: steam at any pressure, any fluid or gas mixture at more than 0.5 bar above atmospheric pressure, or a gas dissolved under pressure in a solvent such as acetylene.1Health and Safety Executive. Safety of Pressure Systems Air compressors, steam boilers, autoclaves, refrigeration plants, and pressurised process piping are the common examples.
Not every pressurised item drags the full compliance burden with it. Where the product of internal pressure in bar and vessel capacity in litres falls below 250 bar-litres, the equipment counts as a “minor system” and is exempt from some requirements, including the formal Written Scheme. Steam is the exception. Any steam system, at any pressure and any size, is subject to the full regulations. Small steam-heated equipment gets overlooked on this point regularly.
Mobile pressure systems are in scope too. A trailer-mounted compressor, welding gas cylinders, or a mobile hydraulic power pack all count. The distinction between installed and mobile matters because it changes who is responsible.2Health and Safety Executive. Pressure Systems Safety Regulations 2000
Who Is Responsible
For an installed system, the user is the dutyholder. The user is whoever has control of the system’s operation, which is not necessarily the legal owner. Lease a boiler and operate it on your premises, and you carry the duties. For a mobile system, the owner holds them instead, even when someone else is running the equipment somewhere else.2Health and Safety Executive. Pressure Systems Safety Regulations 2000
A supplier of an installed system can take on responsibility in writing for the Written Scheme, operation, maintenance, and record keeping. This is common with hired or leased equipment. Even so, you should confirm the scheme is in place and the examination certificate is current. Assuming the supplier has it covered, without checking, is a recurring problem during HSE visits.
The Written Scheme of Examination
You cannot legally operate a qualifying pressure system without a Written Scheme of Examination. It is the central compliance document, and it dictates what gets inspected and when.2Health and Safety Executive. Pressure Systems Safety Regulations 2000
Under Regulation 8, the scheme must cover all protective devices such as relief valves, bursting discs, and pressure switches; every pressure vessel and pipeline where a defect could create danger; and any sections of pipework carrying the same risk. Each part must be individually identified. The scheme also specifies the nature and frequency of each examination, sets out any preparation needed to make the system safe for inspection, and where appropriate requires an examination before first use.3Legislation.gov.uk. The Pressure Systems Safety Regulations 2000 – Regulation 8
The scheme must be drawn up or certified by a competent person. Self-certification is not allowed. The person deciding what gets inspected should not be the person paying for the inspection.
Who Counts as a Competent Person
The competent person certifies the Written Scheme, carries out the examinations, writes the reports, and decides what to do if something dangerous turns up. The regulations define the role broadly. It can be an individual or an organisation, provided they have appropriate practical knowledge and relevant experience of the equipment being assessed.2Health and Safety Executive. Pressure Systems Safety Regulations 2000
Independence is not optional. The competent person must sit outside the operating side of the business. Where a large company uses an in-house competent person, that individual needs enough authority to stop equipment running without asking production managers first. Most businesses use an external inspection body: an insurer’s engineering inspection service or a specialist third-party firm.
The regulations do not require the competent person to hold professional indemnity insurance. Many carry it commercially, but competence, independence, and authority to act are what the law asks for.
How Often the Inspection Must Happen
The PSSR sets no fixed national intervals. The competent person decides the frequency for each system and writes it into the scheme. That decision reflects the type of equipment, the fluid it contains, its age, its operating conditions, its maintenance history, and its condition at the last examination.
The Safety Assessment Federation (SAFed) publishes benchmarks that give a rough guide:
- Steam boilers: 14 months
- Air receivers, external examination: 26 months
- Refrigeration plant: 2 to 6 years, depending on refrigerant, size, and condition
- Other systems: set individually by the competent person
These are starting points. A competent person can justify a longer interval for well-maintained equipment with a strong record, or a shorter one for ageing plant or aggressive service. Postponement of a due examination is possible in specific circumstances, but it has to be documented and justified.
What the Inspection Actually Involves
The examination follows whatever the Written Scheme requires. In practice it combines visual inspection with non-destructive testing. External visual checks look for corrosion, leaks, mechanical damage, and deterioration of lagging or insulation. Internal inspections, where the scheme calls for them, assess wall thinning, pitting, cracking, and deposits that could compromise the vessel.
Non-destructive testing fills in what the eye cannot see. Ultrasonic thickness gauging measures wall thickness without damaging the equipment, which matters for vessels that are hard to open or have restricted internal access. Magnetic particle inspection and dye penetrant testing pick up surface cracks that would otherwise be invisible.
Functional testing of protective devices is the part no one should shortcut. Relief valves, bursting discs, and pressure switches must be confirmed to activate at their correct set pressures. A relief valve that sticks or lifts at the wrong pressure removes the safety case for the whole system. Each device is checked against the safe operating limits established for the equipment.
Where pressure testing is needed during commissioning or after major repairs, hydrostatic testing with water is generally preferred over pneumatic testing with compressed air or gas. Water is incompressible, so a failure during a hydrostatic test releases far less energy. Pneumatic testing carries a genuine explosion risk and is used only where the hydrostatic option is impractical, with extra precautions.
The Report and Imminent Danger Findings
After each examination the competent person produces a written report. It states whether the equipment is safe to keep operating, identifies any repairs needed, confirms the safe operating limits, and gives the date for the next examination. You must keep these reports for as long as the equipment stays in service and make them available to the enforcing authority on request.2Health and Safety Executive. Pressure Systems Safety Regulations 2000
If the examination finds that the equipment could cause imminent danger by continuing in service, the competent person must tell the user or owner immediately, before leaving the site. The system comes out of service until the danger is dealt with. A report on the defect also has to go to the enforcing authority, normally the HSE or the local authority, within 14 days. This is the moment deferred maintenance stops being a paperwork issue and becomes an operational one.
Penalties for Getting It Wrong
The PSSR is enforced under criminal law through the Health and Safety at Work etc. Act 1974. Breaches can lead to prosecution of the business and, in serious cases, of individual directors or managers personally.4Legislation.gov.uk. Health and Safety at Work etc. Act 1974 – Section 33 Sentencing guidelines link fines to the level of harm caused and the turnover of the business, with no upper cap for the most serious cases. A single serious failing at a larger company can run well into six figures.
Alongside fines, the HSE can issue improvement notices that require specific corrective action by a deadline, or prohibition notices that stop equipment or entire operations immediately. There is no appeal delay on a prohibition notice. The plant stops when the inspector says it stops. Gross negligence in the worst cases can carry imprisonment.
The costs that hit hardest usually sit outside the court judgment. An invalidated insurance policy leaves the business absorbing the full loss from any incident. A shutdown means lost production with no compensation. The reputational damage from a preventable explosion or scalding follows a business for years. Keeping the Written Scheme current, examinations on schedule, and reports on file is a smaller undertaking than any of that.